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BACILLUS ANTHRAX
Dr.Baha ,Hamdi AL-AmiediPh. D.Microbiology
BACILLUS
ANTHRACIS
BACILLUS ANTHRAXDr.Baha ,Hamdi AL-Amiedi
Ph. D.Microbiology
Bacillus:General characters
Anthrax is a zoonotic disease (could be transferred from animals to humans) caused by the spore-producing bacterium Bacillus anthracis.
It is Gram positive ,non-motile, rod shape, spore bearing, Aerobic bacilli occurring in chains. Two pathogenic species :
Bacillus anthracis: causes Anthrax disease
Bacillus cereus : causes (food poisoning )
gastroenteritis
Bacillus anthracis
Causces anthrax, a disease especially prevalent in goats, sheep, and cattle
It is a spore former, spores is very stable, resistant to dry , heat, Ultraviolent light play an important role in transmission to human & cause infection, they can survive in soil or skin of animals for years. It is unique in that it is only bacterium with
capsule composed protein(poly-D-glutamic acid )
Clinical manifestation
Bacillus anthracis causes three different
forms of anthrax:
1-cutaneous anthrax
2-Pulmonary anthrax
3-gastrointestinal anthrax
Cutaneous anthrax
the most common naturally occurring
form
of the disease and is characterized by
local inflamatory necrotic lesion (eschar)
at the site of inoculation transmitted
through contact with spores in the
infected animals or animal products
(wool, hair, bone)
Cutaneous Anthrax
PULMONARY ANTHRAX
Also called( Woolsorters disease) : is a
highly fatal form of disease
characterized by rapid and massive
edema in the cheast followed by
cardiovascular shock and death
transmitted occurs when spores
inhaling from infected animals or animals
products
PULMONARY ANTHRAX
Inhalation of the dust or
filaments of wool from
infected animals,
particularly in wool
factories ( wool sorter’s
disease)
Haemotogenous spread –
50% meningitis
Chest X-ray
Chest X-rays is advised as an initial method of
inhalation anthrax detection, but it is
sometimes not useful for patients without
symptoms.
Find a widened mediastinum and pleural
effusion.
At day 1 At day 3
Gastroingtestinal anthrax
Which result from ingestion of spores ,
is very rare but highly fatal
transmitted when spores from infected
animals or animals products these spores
are ingested
INTESTINAL ANTHRAX
Consumption of improperly cooked
infected meat.
Causes violent enteritis with bloody
diarrhoea
All clinical conditions lead to septicaemic anthrax if
not treated early – Highly fatal!!!
Pathogenesis/Virulence factors
Bacillus anthracis contain several
virulence factors:
a- A capsule of D-glutamic acid is anti-
phagocytes and helps the
microorganism to evade the immune
system of the host
Pathogenesis/Virulence factors
b- three exotoxins are product :
1-protactive antigen(PA): bind the
anthrax toxin receptor (ATR) on the
surface of host cells and facilitates the
translocation of the 2 (other
exotoxins, edema factor (EF) and the
lethal factor (LF) into the cell.
2-Edema factor ( EF): is an adenlyate
cyclase that increase intracellular
cAMP Stimuling an efflux of fluids and
ions that results in edema
3-Lethal Factor (LF) is a mitogen –
activated protein kinase kinase
(MAPKK) protease that
Disrupts cell signaling causing cell death
& tissue necrosis.
Mod of action of anthrax Toxin
Laboratory diagnosis
1-smear prepared from exudates, sputum
show gram positive bacilli, non-sporing
bacilli occur in chain
2-cultur: the material is inoculated on
Nutrient Agar & Blood Agar non-
hemolysin, with medosa head shape
appearance ,smear from cultur shows
gram positive bacilli spore in the center
of bacili with chain arrange
Microscopy
Gram stain – for
bacilli demonstration
McFadyean’s reaction
– for capsule
demonstration.
Spore staining – for
spore demonstration.
Gram stain
McFadyaen’s reaction
Spore stain
Culture
Other non-selective media
Nutrient agar –colonies – medusa head
appearance on low power microscopy
Blood agar – usually non-haemolytic
Laboratory diagnosis
3-Macfadyen test: it is special stain for capsular of bacillus anthracis
4-Serological test(Ascoli Test): it is precipitate & rapid diagnosis zone of precipitate at junction of tissue extract & antiserum within 5 minutes at room temperature means positive result of Ascoli Test.
5-Animal inoculation: injected subcutaneously in guinea big which dies within 36-48 hours, smear from heart blood & spleen show gram positive bacilli
Ascoli Test
http://microbewiki.kenyon.edu/index.php/Anthrax
https://sites.google.com/site/allmicrobiologysite/medic
al-microbiology-ii/summary-of-bacterial-
pathogens/bacillus-anthracis
http://www.cdc.gov/anthrax/
http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAutoListName/Page/1204619483853
References